Landing gear strut-to-ski ball socket connection

ABSTRACT

An articulate connection for attaching a snow ski to the landing strut of an airplane and including structural features whereby the associated ski may not only oscillate about a horizontal transverse axis relative to the strut but also oscillate, in a limited manner, about an axis generally paralleling the ski.

United States Patent [1 1 Kubek 1 Oct. 30, 1973 LANDING GEARSTRUT-TO-SKI BALL SOCKET CONNECTION [75] Inventor: John Kubek,Anchorage, Alaska [73] Assignee: Maxweldon Sides, Anchorage,

Alaska a part interest 22 Filed: Jan. 28, 1972 21 Appl. No.: 221,525

[52] US. Cl. 244/108, 280/25 [51] Int. Cl. B64c 25/52 [58] Field ofSearch 244/108, 105, 101, 244/100 R; 280/14, 26, 28, 7.14, 25; 287/88,

[56] References Cited UNITED STATES PATENTS Landes 244/108 4/1962 Dworak280/26 4/1965 Gandy 287/87 X Primary Examiner-Milton Buchler AssistantExaminer-Paul E. Sauberer Attorney-Harvey B. Jacobson [57] ABSTRACT Anarticulate connection for attaching a snow ski to the landing strut ofan airplane and including structural features whereby the associated skimay not only oscillate about a horizontal transverse axis relative tothe strut but also oscillate, in a limited manner, about an axisgenerally paralleling the ski.

2 Claims, 6 Drawing Figures Patented Oct. 30,1973 I 3,768,758

2 Sheets-Sheet 1 Patented Oct. 30, 1973 13,76,758

2 Sheets-Sheet 2 LANDING GEAR STRUT-TO-SKI BALL SOCKET CONNECTION Lightaircraft are provided, in most instances, with downwardly and outwardlydivergent wheel supporting struts when the aircraft does not includeretractable landing gear. This type of fixed landing gear is resilient,at least to some degree, and the lower ends of the landing struts fromwhich the landing wheels are journaled to splay outwardly upon impact ofthe aircraft with the ground during landing operations. As long as suchlightweight aircraft provided with fixed landing gear are also equippedwith landing wheels and not skis, no difficulty is encountered inasmuchas the wheels may roll along the ground in cambered positions and stillabsorb appreciable shock due to their resiliency. However, when lightaircraft including fixed landing gear have snow skis mounted on theirlanding struts in lieu of wheels, if the skis are positioned so as to behorizontal when the struts are unladen while the aircraft is in the airin order to enable the skis to be in noncambered positions upon initialcontact of the skis with the ground, the inherent outward splaying ofthe lower ends of the landing struts from which the skis are supportedresults in the skis being positively cambered so that the maximum shockoflanding is carried by the inside edges of the skis. Inasmuch as theskis are not resilient to the extent of conventional landing wheels andthe maximum landing shock is centered along the inside edges of theskis, the latter are often over stressed to the point of failure. Whilethe possibility of ski failure could be at least partially reduced bythe utilization of more heavily constructed skis, the substitution ofskis on light aircraft in lieu of landing wheels loads the aircraft moreheavily and the utilization of even more heavily constructed skis wouldfurther load the aircraft and reduce its performance both in the air andwhile taking off.

It is accordingly the main object of this invention to provide a meanswhereby landing skis for light aircraft provided with fixed landing gearof the type embodying downwardly and outwardly inclined struts may besupported from those struts for limited oscillation about axes generallyparalleling the skis. In this manner, and with the skis hung in pendulumfashion from the lower ends of the struts, the under surfaces of theskis may be maintained parallel with the ground even during flexing inthe form of outward splaying of the lower ends of the landing strutsfrom which the skis are supported.

Another object of this invention, in accordance with the immediatelypreceding object, is to provide an articulated joint between the landingstruts of aircraft and snow skis supported therefrom which will enablethe skis to be quickly mounted upon those spindle portions carried bythe lower ends of the struts from which conventional landing wheels areusually journaled.

Yet another object of this invention is to provide a strut-to-skiconnection enabling snow skis to be readily mounted upon substantiallyall lightweight aircraft conventionally provided with landing wheels.

A final object of this invention to be specifically enumerated herein isto provide a strut-to-ski connection for light aircraft which willconform to conventional forms of manufacture, be of simple constructionand easy to install so as to provide a device that will be economicallyfeasible, long lasting and relatively trouble free.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout and in which:

FIG. 1 is a fragmentary side elevational view of the lower forwardfuselage portion of a lightweight aircraft illustrating a snow skisupported from the near side landing strut of the aircraft by means ofthe improved strut-to-ski connection of the instant invention;

FIG. 2 is a fragmentary transverse vertical sectional view takensubstantially upon the plane indicated by the section line 2-2 of FIG. Iand on somewhat of an enlarged scale;

FIG. 3 is a fragmentary iongitudinal vertical sectional view takensubstantially upon the plane passing through the center of thestrut-to-ski connection;

FIG. 4 is an enlarged fragmentary transverse vertical sectional viewtaken substantially upon the plane passing through the center of thestrut-to-ski connection;

FIG. 5 is a fragmentary front elevational view of a conventional form oflight aircraft provided with fixed landing gear and illustrating themanner in which the wheels of the aircraft splay outwardly upon impactof the aircraft landing wheels with the ground, FIG. 5 clearlyillustrating the change in camber as the aircraft lands; and

FIG. 6 is a fragmentary elevational view similar to FIG. 5 butillustrating the manner in which the strut-toski connection of theinstant invention enables the associated snow skis to obtain theirhorizontal positions so as to prevent the inside edges of the skis frombeing overly stressed.

Referring now more specifically to the drawings the numeral 10 generallydesignates a conventional lightweight aircraft including downwardly andoutwardly divergent landing gear struts l2 hung from the underside ofthe fuselage 14 of the plane or aircraft 10 in any conventional manner.As may be seen from FIG. 5 of the drawings the lower ends of the strutsl2 conventionally have landing wheels 16 journaled therefrom and thestruts l2 assume a position, when unloaded, supporting the wheels 16 indownwardly convergent positions. However, as may be noted from thephantom line illustration in FIG. 5, as the aircraft 10 impacts with theground 18 the lower ends of the struts 12 are splayed outward so thatwhen maximum loading of the struts occurs the wheels 16 will be disposedin substantially upright position.

Initially, if snow skis were to be supported from the struts 12 in amanner such that the skis were cambered in the inclined positions of theWheels 16 illustrated in solid lines in FIG. 5 of the drawings, when theaircraft 10 lands the outside edges of the skis would have a tendency tocut into the snow covered ground upon which the aircraft is landing andif there was any cross wind the lateral movement of the aircraft at theinstant of impact with the ground in conjunction with the cambered skion the downwind side of the aircraft would tend to cause the downwindski to dig into the ground in a manner such that the downwind wing tipmight contact the ground and cause the aircraft to ground loop. On theother hand, if skis were mounted on the lower ends of the struts 12 intheir unloaded condition with the skis horizontally disposed, theoutward splaying of the lower ends of the struts upon contact of theaircraft with the ground will cause the maximum loading of the aircrafton the skis to be carried by the inside edgess of the skis. Therefore,the strut-to-ski connection of the instant invention has been designedto enable the skis carried by the fixed landing struts of the lightaircraft to oscillate slightly about their longitudinal axes thusallowing the undersurfaces of the skis to parallel to the ground at alltimes.

In FIGS. 1-4 and 6 of the drawings the aircraft 10 is provided with snowskis referred to in general by the reference numerals and the skis 20include ski members 22 and central upwardly projecting body portions 24by which the skis 20 are supported from the lower ends of the struts I2.

Conventionally, the struts 12 include laterally outwardly projecting andgenerally horizontal spindle portions 25 from which wheels such as thewheels 16 in FIG. 5 are journaled. ln order to facilitate readyreplacement of such wheels 16 with the skis 20, the skis 20 areconstructed in a manner whereby they may be oscillatably supported fromthe same stub axles 25.

With attention now invited more specifically to FIG. 4 of the drawingsit may be seen that the upper portion of the body portion 24 has aspherical socket 26 molded therein. Within the socket 26 is disposed aspherical ball 30 and the ball 30 is provided with a diametric bore 32whose opposite ends are registered with vertically elongated slots 34formed in the opposite sides of the body 24. The slots 34 are disposeddiametrically opposite each other in relation to the socket 26 and acylindrical sleeve 36 is secured through the bore 32. The bore 32includes axially spaced circumferential grooves 38 in whichcircumferential ribs 40 formed on the sleeve 36 are seated. Finally,bearing sleeves 42 are secured within the opposite ends of the sleeve 36in axially spaced relation. lnitially, the ball 30 may be molded and thebody 24 molded about the ball. Thereafter, the sleeve 36 may be insertedor molded within ball 30 and the sleeves 42 may be thereafter insertedinto and bonded in place within the opposite ends of the sleeve 36.Then, each ski 20 may be journaled on the corresponding stub axle 25with any suitable means being utilized to retain the sleeves 42 againstaxial shifting relative to the stub shafts 25.

From FIG. 4 of the drawings it may be seen that the skis 20 may thus beoscillated about axes generally paralleling the ski members 22 andextending through the center of the ball 30. By this construction, thechange in camber of the struts 12 did not affect the camber of the skis20 and the under surfaces of the ski members 22 thereof may alwaysparallel the ground surface upon which the aircraft is landing or fromwhich the aircraft 10 is departing. The center of gravity of the skis 20is, of course, disposed below the elevation of the center of the balls30 and thus, the skis 20 tend to naturally assume horizontally positionsby gravity. In this manner, the skis are substantially horizontallydisposed upon initial contact with the ground and also horizontallydisposed when the struts 12 are loaded to their maximum during landingoperations.

The materials of which the various components of the skis 20 may beformed are numerous. Plastics as well as certain metals may be used andthe ball and socket connection defined by the ball 30 and socket 26provides sufficient strength to support the skis 20 from the lower endsof the struts 12. If it is desired, the upper portion of the bodyportion 24 in which the socket 26 is formed can be constructed as aseparate part and secured to the lower portion of the body portion 24 inany convenient manner enabling the ball and socket connection defined bythe upper body portion to be readily replaced, when desired.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. In combination with a light aircraft having a downwardly andlaterally outwardly inclined landing strut of the type including an axleend upon which a landing wheel may be journaled, a spherical ball memberhaving a diametric sleeve secured therethrough and journaled on saidaxle end for rotation about the longitudinal axis of said axle end and adiameter of said ball member, an elongated horizontal ski member havinga central upwardly projecting body portion, an upper portion of saidbody portion having a spherical cavity formed therein in which said ballmember is captively received with said axle end portion extendinghorizontally and transverse to said ski, the opposite ends of saidsleeve projecting outwardly of opposite sides of said ball member, saidupper portion of said body having upstanding slots formed therein onopposite sides of and opening into said cavity and through which theopposite ends of said sleeve project and in which said sleeve ends aresiidably guidingly received for limiting oscillation of said ski memberrelative to said ball member toangular displacement about a horizontalaxis passing along a diameter of said ball member and generallyparalleling said ski, said sleeve ends having bearing sleeve meanssecured therein through which said axle end portion is journaled.

2. The combination of claim 1 wherein said sleeve and ball memberinclude coacting means locking said sleeve within said ball memberagainst axial shifting of said sleeve relative to said ball member.

1. In combination with a light aircraft having a downwardly andlaterally outwardly inclined landing strut of the type including an axleend upon which a landing wheel may be journaled, a spherical ball memberhaving a diametric sleeve secured therethrough and journaled on saidaxle end for rotation about the longitudinal axis of said axle end and adiameter of said ball member, an elongated horizontal ski member havinga central upwardly projecting body portion, an upper portion of saidbody portion having a spherical cavity formed therein in which said ballmember is captively received with said axle end portion extendinghorizontally and transverse to said ski, the opposite ends of saidsleeve projecting outwardly of opposite sides of said ball member, saidupper portion of said body having upstanding slots formed therein onopposite sides of and opening into said cavity and through which theopposite ends of said sleeve project and in which said sleeve ends areslidably guidingly received for limiting oscillation of said ski memberrelative to said ball member to angular displacement about a horizontalaxis passing along a diameter of said ball member and generallyparalleling said ski, said sleeve ends having bearing sleeve meanssecured therein through which said axle end portion is journaled.
 2. Thecombination of claim 1 wherein said sleeve and ball member includecoacting means locking said sleeve within said ball member against axialshifting of said sleeve relative to said ball member.